linux-kernel - Re: [PATCH v1 1/1] gpio: pca953x: Improve bias setting

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Message-ID: <CAMpxmJWG1rO69i9WmFu-a23W2cjNtabyySoAyOB-NXCN5VjNHw@mail.gmail.com>
Date:   Fri, 1 Oct 2021 11:58:31 +0200
From:   Bartosz Golaszewski <bgolaszewski@...libre.com>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:     linux-gpio <linux-gpio@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>
Subject: Re: [PATCH v1 1/1] gpio: pca953x: Improve bias setting

On Fri, Sep 24, 2021 at 12:46 AM Andy Shevchenko
<andriy.shevchenko@...ux.intel.com> wrote:
>
> The commit 15add06841a3 ("gpio: pca953x: add ->set_config implementation")
> introduced support for bias setting. However this, due to being half-baked,
> brought potential issues:
>  - the turning bias via disabling makes the pin floating for a while;
>  - once enabled, bias can't be disabled.
>
> Fix all these by adding support for bias disabling and move the disabling
> part under the corresponding conditional.
>
> While at it, add support for default setting, since it's cheap to add.
>
> Fixes: 15add06841a3 ("gpio: pca953x: add ->set_config implementation")
> Cc: Thomas Petazzoni <thomas.petazzoni@...tlin.com>
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> ---
>  drivers/gpio/gpio-pca953x.c | 16 +++++++++-------
>  1 file changed, 9 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/gpio/gpio-pca953x.c b/drivers/gpio/gpio-pca953x.c
> index f5cfc0698799..dac4d772a4d1 100644
> --- a/drivers/gpio/gpio-pca953x.c
> +++ b/drivers/gpio/gpio-pca953x.c
> @@ -566,21 +566,21 @@ static int pca953x_gpio_set_pull_up_down(struct pca953x_chip *chip,
>
>         mutex_lock(&chip->i2c_lock);
>
> -       /* Disable pull-up/pull-down */
> -       ret = regmap_write_bits(chip->regmap, pull_en_reg, bit, 0);
> -       if (ret)
> -               goto exit;
> -
>         /* Configure pull-up/pull-down */
>         if (config == PIN_CONFIG_BIAS_PULL_UP)
>                 ret = regmap_write_bits(chip->regmap, pull_sel_reg, bit, bit);
>         else if (config == PIN_CONFIG_BIAS_PULL_DOWN)
>                 ret = regmap_write_bits(chip->regmap, pull_sel_reg, bit, 0);
> +       else
> +               ret = 0;
>         if (ret)
>                 goto exit;
>
> -       /* Enable pull-up/pull-down */
> -       ret = regmap_write_bits(chip->regmap, pull_en_reg, bit, bit);
> +       /* Disable/Enable pull-up/pull-down */
> +       if (config == PIN_CONFIG_BIAS_DISABLE)
> +               ret = regmap_write_bits(chip->regmap, pull_en_reg, bit, 0);
> +       else
> +               ret = regmap_write_bits(chip->regmap, pull_en_reg, bit, bit);
>
>  exit:
>         mutex_unlock(&chip->i2c_lock);
> @@ -594,7 +594,9 @@ static int pca953x_gpio_set_config(struct gpio_chip *gc, unsigned int offset,
>
>         switch (pinconf_to_config_param(config)) {
>         case PIN_CONFIG_BIAS_PULL_UP:
> +       case PIN_CONFIG_BIAS_PULL_PIN_DEFAULT:
>         case PIN_CONFIG_BIAS_PULL_DOWN:
> +       case PIN_CONFIG_BIAS_DISABLE:
>                 return pca953x_gpio_set_pull_up_down(chip, offset, config);
>         default:
>                 return -ENOTSUPP;
> --
> 2.33.0
>

Applied, thanks!

Bart